Operating mechanism



Feb, 5, 1957 F. STEINER ETAL 2,780,105

OPERATING MECHANISM Filed July 15, 1955 Inventor E. DINSTL ESTE INER V Attorney OPERATING MECHANISM Application July 15, 1953, Serial No. 368,079

3 Claims. (Cl. 7410.7)

This invention relates to an operating mechanism for converting a uniform linear motion into a non-uniform linear motion to be imparted to a travelling member such as the tuning core of an inductance.

The method of tuning oscillating circuits by varying the inductance of a coil in the circuit is known to the art. This is advantageously accomplished by displacing a core such as a high-frequency core. In order to obtain favorable variation characteristics the coils are of the extended type with long cores. The cores are generally moved by a pull applied to a cord or by means of a rack and pinion.

The method of obtaining any desired inductance in tuning of the core by using cores having different cross sections is known to the art. Technologically, certain diffi ulties arise in the manufacture of such cores, which increase the cost of the arrangement.

In addition, according to another well-known embodiment, a cord moving over an eccentric disk and kept under a constant tension by a spring is used to obtain any desired inductance. When this eccentric disk is rotated, the cord moves unequal distances per winding unit depending on the curve of the eccentric disk, and the core attached to the cord is moved variable distances, thus varying the inductance in accordance with the position of the eccentric disk.

The disadvantages of this embodiment are the difficult and costly manufacture of the eccentric disk. Faults in the cord drum eccentricity and its curve shape are transmitted undiminished to the tuning.

The purpose of the invention is to obviate these difficulties, namely the eifects of the manufacturing tolerances, and to provide in a simple manner adjustable permeability tuning.

The invention consists of an arrangement for the permeability tuning of a tuned circuit by moving the core by means of a cord passing over a drum and, if necessary, over reversing rollers, and subjected to a constant tension by a spring, characterized in that, in order to obtain a desired inductance as a function of the angle of rotation of the drum, the cord is deflected by a cam follower member that slides over a portion of the curve corresponding to the desired inductance variation, and thus for each adjusted angular unit of the drum the tuning circuit core is moved a greater or lesser amount.

By means of the arrangement according to the invention, the variations in the curve are transmitted diminished to the tuning (which was not the case with the eccentric cord drum), because the angle formed by the cord in the guiding member may be kept at approximately 180.

In spite of dispersion losses along the core, good tuning characteristics are obtained because, in accordance with a further feature of the invention, the position of curved plates may be made adjustable.

One embodiment example of the invention will now be described in greater detail with reference to the drawing in which Fig. 1 is a diagram of the operating mechanism and Fig. 2 a sectional view (enlarged) on the line nited States Patent 2-2 of Fig. l. Coil 1 is tuned by means of movable core 2 constituting a travelling member, made of highfrequency core material.

The core is moved by a first flexible cable or pull cord 3. In the embodiment example, the cord 3 is fastened at a point 10, and passes over reversing pulley 7, which holds the cord taut by means of spring 9, to one end of high-frequency core 2, where it is fastened. At the other end high-frequency core 2 is fastened to a second flexible cable or cord 3', which is led over reversing roller 8 to a cam follower 4, which in this case is a U-shaped rider, is wound up more or less (depending on the tuning) on a circular cord drum 6, and is fastened at point 11 on this drum which is adapted to be rotated by a knob 6. Cord 3 is connected to a U-shaped cam follower member 4 by means of a set screw 4 (Fig. 2). This screw may be loosened so that the cam follower member 4 may be secured at any point on the cord 3'.

When drum 6 is rotated in the clockwise direction, cam follower member 4 moves to the right along contoured edge 12 of plate 5, while core 2 is moved to the left into coil 1. Pulley 7 is drawn to the left by spring 9, so that the cord remains under tension.

The two arms of the member 4 embrace the contoured edge of the cam member 5 which comprises a plate 5 secured and adjusted in position by screws 5' one of which passes through a dot 5 whereby the plate may be turned about the axis of the other screw 8 so as to compensate for manufacturing tolerances.

The cords 3 and 3' may be made of textile, synthetic material or metal wire. Alternatively strong spiral springs or elastic bands may be used.

The cam follower member 4 or the cam plate 5 may be made of insulating material or metal, or they may be made partly of insulating material and partly of metal.

The contour of the edge of the plate 5 will vary in accordance with the desired inductance variations. When the tuned circuit is used as the first circuit of an input band filter, and the second circuit is tuned by means of a rotary condenser, the contour is also determined by the capacity variations of the rotary condenser which is used.

Other means may be provided for the cam member and cam follower. For example, the edge of the plate 5 may be grooved and the shank of a pin shaped like a thumbtack may slide in the groove. In this case the cord 3 would be secured to the head of the pin. Alternatively, curved slots may be formed in two plates spaced apart from one another and a pin or double thumbtacklike member arranged to slide in the slot. In this lastmentioned arrangement the cord 3 will be connected to the mid point of the double thumbtack-like member and the cord 3 will pass between the two slotted plates.

It is also possible to use a wire as the contoured member and have a sleeve slide along it as the cam follower member. This embodiment has the advantage that, in addition to the wire being movable within a plane, subsequent adjustment may be made by bending the wire slightly and by just the right amount.

We claim:

1. An operating mechanism for converting a uniform linear motion into a non-uniform linear motion to be imparted to a travelling member, comprising spring means, a first flexible cable coupled at one end to said travelling member and at its other end to said spring means, a second cable coupled at one end to the opposite end of said travelling member, a roller, a driving drum, said second cable being passed around said roller in one direction and around said drum in an opposite direction, means attaching the other end of said second cable to the periphery of said drum, a fixed cam member mounted between said drum and roller and having a predetermined contour and extending in a plane parallel to the plane in which said second cable moves and a cam follower fastened to a predetermined point on said second cable so as to ride on the contour of said cam member upon rotation of said drum.

2. An operating mechanism according to claim 1, wherein said fixed cam member comprises a plate having a contoured edge and said cam follower comprises a U-shaped member, the arms of which embrace said contoured edge.

3. An operating mechanism according to claim 2 further comprising means for adjusting the position of said plate.

References Cited in the file of this patent UNITED STATES PATENTS 

